Energy storage element

Abstract

To provide an energy storage element that can be miniaturized or have increased capacity. [Solution] An energy storage element comprising a first electrode body 600 formed by winding a first electrode plate and a second electrode body 700 formed by winding a second electrode plate, wherein the first electrode body has a first positive electrode tab 620 and a first negative electrode tab 630 protruding from a part of the first electrode body main body 610, and the second electrode body has a second positive electrode tab 720 and a second negative electrode tab 730 protruding from a part of the second electrode body main body 710, the first electrode body main body has a first electrode plate end portion 612b at a position facing the second electrode body main body, and the second electrode body main body has a second electrode plate end portion 711b at a position facing the first electrode body main body, and the first electrode plate end portion and the second electrode plate end portion are arranged in positions that do not overlap when viewed from the direction in which the first electrode body and the second electrode body are aligned.

Description

Technical Field

[0001] The present invention relates to a power storage element including a plurality of electrode bodies in which electrode plates are wound and tabs are provided.

Background Art

[0002] Conventionally, a power storage element including a plurality of electrode bodies in which electrode plates are wound and having tabs is known. Patent Document 1 discloses a rectangular secondary battery (power storage element) including a plurality of flat wound groups (electrode bodies) in which a positive electrode and a negative electrode are wound and having tabs.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a power storage element in which an electrode body with wound electrode plates is housed in a container, generally, an electrode body having a tab as in the above conventional power storage element can occupy a larger proportion in the container than an electrode body without a tab. Therefore, in a configuration including an electrode body having a tab as in the above conventional power storage element, generally, miniaturization or high capacity of the power storage element can be achieved. However, even in a configuration including an electrode body having a tab as in the above conventional power storage element, when a plurality of electrode bodies are arranged, a wasteful space may occur between the plurality of electrode bodies. In such a case, there is a risk of increasing the size or reducing the capacity of the power storage element, and miniaturization or high capacity of the power storage element cannot be achieved.

[0005] The present invention has been made by the inventors of the present application newly paying attention to the above problems, and an object thereof is to provide a power storage element capable of achieving miniaturization or high capacity.

Means for Solving the Problems

[0006] An energy storage element according to one aspect of the present invention comprises a first electrode body formed by winding a first electrode plate and a second electrode body formed by winding a second electrode plate, wherein the first electrode body has a first electrode body main body and tabs protruding from a part of the first electrode body main body, which are positive electrode tabs and negative electrode tabs, respectively; the second electrode body has a second electrode body main body and tabs protruding from a part of the second electrode body main body, which are positive electrode tabs and negative electrode tabs, respectively; the first electrode body main body has a first electrode plate end portion, which is the end of the winding of the first electrode plate, at a position facing the second electrode body main body; the second electrode body main body has a second electrode plate end portion, which is the end of the winding of the second electrode plate, at a position facing the first electrode body main body; and the first electrode plate end portion and the second electrode plate end portion are arranged in positions that do not overlap when viewed from the direction of alignment of the first electrode body and the second electrode body.

[0007] This invention can be realized not only as such an energy storage element, but also as a combination of a first electrode body and a second electrode body. [Effects of the Invention]

[0008] The energy storage element according to the present invention can be miniaturized or have its capacity increased. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view showing the external appearance of an energy storage element according to an embodiment. [Figure 2] Figure 2 is an exploded perspective view showing the individual components of the energy storage element according to the embodiment. [Figure 3] Figure 3 is a perspective view showing the configuration of the first electrode body and the second electrode body according to the embodiment. [Figure 4] Figure 4 is a top view showing the configuration of the first electrode body according to the embodiment. [Figure 5]Figure 5 is a top view showing the configuration of the second electrode body according to the embodiment. [Figure 6] Figure 6 is a top view showing the positional relationship between the first electrode body and the second electrode body according to the embodiment. [Figure 7] Figure 7 is a top view showing an example of the arrangement of tabs for the first electrode body and the second electrode body according to a modified example 1 of the embodiment. [Figure 8] Figure 8 is a top view showing an example of the arrangement of the starting ends of the electrode plates of the first electrode body and the second electrode body according to a modified example 2 of the embodiment. [Figure 9] Figure 9 is a top view showing an example of the arrangement positions of the electrode plate start ends and tabs of the first electrode body and the second electrode body according to a modified example 3 of the embodiment. [Modes for carrying out the invention]

[0010] An energy storage element according to one aspect of the present invention comprises a first electrode body formed by winding a first electrode plate and a second electrode body formed by winding a second electrode plate, wherein the first electrode body has a first electrode body main body and tabs protruding from a part of the first electrode body main body, which are positive electrode tabs and negative electrode tabs, respectively; the second electrode body has a second electrode body main body and tabs protruding from a part of the second electrode body main body, which are positive electrode tabs and negative electrode tabs, respectively; the first electrode body main body has a first electrode plate end portion, which is the end of the winding of the first electrode plate, at a position facing the second electrode body main body; the second electrode body main body has a second electrode plate end portion, which is the end of the winding of the second electrode plate, at a position facing the first electrode body main body; and the first electrode plate end portion and the second electrode plate end portion are arranged in positions that do not overlap when viewed from the direction of alignment of the first electrode body and the second electrode body.

[0011] According to this, in the energy storage element, the first electrode body around which the first electrode plate is wound has a first electrode body main body, a first positive electrode tab, and a first negative electrode tab, and the second electrode body around which the second electrode plate is wound has a second electrode body main body, a second positive electrode tab, and a second negative electrode tab. The first electrode plate end portion of the first electrode body main body facing the second electrode body main body and the second electrode plate end portion of the second electrode body main body facing the first electrode body main body are positioned so as not to overlap. In this way, the first electrode plate end portion of the first electrode body main body is positioned so as to face the second electrode body main body, and the second electrode plate end portion of the second electrode body main body is positioned so as to face the first electrode body main body and so as not to overlap with the first electrode plate end portion. This makes it possible to suppress the occurrence of wasted space between the first electrode body and the second electrode body (between the first electrode body main body and the second electrode body main body), thereby enabling miniaturization or increased capacity of the energy storage element.

[0012] The direction from the first positive electrode tab toward the first negative electrode tab and the direction from the second positive electrode tab toward the second negative electrode tab may be the same direction.

[0013] The configuration in which the first electrode plate end of the first electrode body is positioned opposite the main body of the second electrode body, and the second electrode plate end of the second electrode body is positioned opposite the main body of the first electrode body, can be achieved by rotating one of the two identical electrode bodies by 180°. However, in this case, the first positive electrode tab and the second positive electrode tab are positioned in opposite directions to the first negative electrode tab and the second negative electrode tab, making it difficult to connect tabs of the same polarity to a single current collector. For this reason, even if the first electrode plate end and the second electrode plate end are positioned as described above, the direction from the first positive electrode tab to the first negative electrode tab and the direction from the second positive electrode tab to the second negative electrode tab are positioned in the same direction. As a result, the first positive electrode tab and the second positive electrode tab are positioned in the same direction relative to the first negative electrode tab and the second negative electrode tab, making it easy to connect tabs of the same polarity to a single current collector.

[0014] At least one of the first positive electrode tab and the first negative electrode tab protrudes and is arranged from a part of a portion of the first electrode body main body portion on the side opposite to the second electrode body main body portion rather than a portion facing the second electrode body main body portion, and a tab having the same polarity as at least one of the second positive electrode tab and the second negative electrode tab may protrude and be arranged from a part of a portion of the second electrode body main body portion on the side opposite to the first electrode body main body portion rather than a portion facing the first electrode body main body portion.

[0015] A configuration in which the first end portion of the first electrode plate of the first electrode body is arranged at a position facing the second electrode body main body portion and the second end portion of the second electrode plate of the second electrode body is arranged at a position facing the first electrode body main body portion can be realized by arranging two identical electrode bodies in the same direction and adjusting the length of the electrode plate. Thereby, since it is possible to easily suppress the generation of a wasteful space between the first electrode body and the second electrode body (between the first electrode body main body portion and the second electrode body main body portion), it is possible to easily achieve miniaturization or high capacity of the power storage element. However, in this case, the tab of either the first electrode body or the second electrode body is arranged at a portion facing the other electrode body. As a result, the distance between the tabs having the same polarity of the first electrode body and the second electrode body becomes close, and due to the concentration of the tabs, a wasteful space may occur or it may become difficult to connect to the current collector. Therefore, at least one tab of the first electrode body is made to protrude from a portion of the first electrode body main body portion on the side opposite to the second electrode body main body portion, and a tab having the same polarity as the tab of the second electrode body is made to protrude and be arranged from a portion of the second electrode body main body portion on the side opposite to the first electrode body main body portion. That is, the tabs having the same polarity of the first electrode body and the second electrode body are arranged on the opposite side of the portion facing each other's electrode body main body portion. Thereby, since the tabs having the same polarity of the first electrode body and the second electrode body are arranged at positions separated from each other, the tabs are dispersed, suppressing the generation of a wasteful space, making it easy to bend the tabs, and enabling easy connection to the current collector.

[0016] At least one of the first electrode body main body portion and the second electrode body main body portion has a pair of curved portions formed by winding at least one of the first electrode plate and the second electrode plate, and a flat portion connecting the pair of curved portions, and at least one of the first electrode plate end portion and the second electrode plate end portion may be disposed on the flat portion.

[0017] According to this, at least one of the first electrode plate end portion and the second electrode plate end portion is disposed on the flat portion of at least one of the first electrode body main body portion and the second electrode body main body portion. Thereby, since the fixing position of the electrode plate end portion in the electrode body can be set to the flat portion, in the electrode body, the electrode plate end portion can be easily fixed with a tape or the like. When flat portions are formed on both the first electrode body main body portion and the second electrode body main body portion, the electrode plate end portion can be sandwiched between the flat portions of both the first electrode body main body portion and the second electrode body main body portion, so that the electrode plate end portion can be easily fixed.

[0018] The first electrode plate end portion may extend toward the second electrode plate end portion at a portion of the first electrode body main body portion facing the second electrode body main body portion, and the second electrode plate end portion may extend toward the first electrode plate end portion at a portion of the second electrode body main body portion facing the first electrode body main body portion.

[0019] According to this, by arranging both the first electrode plate end portion and the second electrode plate end portion to extend toward each other in the first electrode body main body portion and the second electrode body main body portion, the total lengths of both the first electrode plate and the second electrode plate can be increased. Thereby, the space between the first electrode body and the second electrode body can be effectively utilized, and the capacities of the first electrode body and the second electrode body can be increased, so that the power storage element can be miniaturized or have a higher capacity.

[0020] The first electrode body further has a first electrode plate starting end, which is the starting portion of the winding of the first electrode plate, and the second electrode body further has a second electrode plate starting end, which is the starting portion of the winding of the second electrode plate. The first electrode plate starting end and the second electrode plate starting end may be positioned so as to be viewed from the direction in which the first electrode body and the second electrode body are aligned, they protrude in opposing directions and do not overlap.

[0021] According to this, the starting end of the first electrode plate of the first electrode body and the starting end of the second electrode plate of the second electrode body are positioned so as not to overlap when viewed from the direction in which the first and second electrode bodies are aligned. This reduces the overlap between the first and second electrode plates, thereby enabling miniaturization or increased capacity of the energy storage element.

[0022] The following description of an energy storage element according to an embodiment (including its modifications) of the present invention will be made with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. Dimensions and other specifications are not strictly illustrated in each figure. In each figure, the same or similar components are denoted by the same reference numerals.

[0023] In the following description and drawings, the direction in which the pair of electrode terminals (positive and negative sides, hereinafter the same) of the energy storage element are aligned, the direction in which the pair of current collectors are aligned, the width direction of the first electrode and the second electrode, or the opposing direction of the short sides of the container is defined as the X-axis direction. The direction in which the first electrode and the second electrode are aligned, the direction in which the electrode plates of the first and second electrode are stacked, the thickness direction of the first and second electrode, the opposing direction of the long sides of the container, or the thickness direction of the container is defined as the Y-axis direction. The direction in which the winding axis of the first electrode and the winding axis of the second electrode extend, the height direction of the first and second electrode, the direction in which the electrode terminals, current collectors, first electrode and second electrode, the direction in which the container body and lid of the container are aligned, or the up and down direction is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Depending on the usage, the Z-axis direction may not be vertical, but for the sake of explanation below, the Z-axis direction will be described as vertical.

[0024] In the following explanation, the X-axis positive direction refers to the direction of the X-axis arrow, and the X-axis negative direction refers to the opposite direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where they are not strictly those directions or orientations. Two directions being orthogonal means not only that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, i.e., that they may have a difference of, for example, a few percent.

[0025] (Embodiment) [1. General description of the energy storage element 10] First, a general description of the energy storage element 10 in this embodiment will be given. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to this embodiment. Figure 2 is an exploded perspective view showing the energy storage element 10 according to this embodiment disassembled to show each component. In Figure 2, the container body 110 of the container 100, one of the components of the energy storage element 10, is not shown.

[0026] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, specifically a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used for power storage or power supply purposes. The energy storage element 10 is used as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and gasoline automobiles. Examples of railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage element 10 can also be used as a stationary battery for household or commercial use.

[0027] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may not be a secondary battery, but a primary battery that allows the user to use the stored electricity without charging. The energy storage element 10 may be a battery using a solid electrolyte. The energy storage element 10 may be a pouch-type energy storage element. In this embodiment, the energy storage element 10 is shown in a flat rectangular parallelepiped shape (square), but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, but may be cylindrical, oval cylindrical, or a polygonal prism shape other than a rectangular parallelepiped.

[0028] As shown in Figure 1, the energy storage element 10 comprises a container 100 (container body 110 and lid 120), a pair of electrode terminals 200 (positive and negative sides), and a pair of upper gaskets 300 (positive and negative sides). Inside the container 100 (container body 110), as shown in Figure 2, are housed a pair of lower gaskets 400 (positive and negative sides), a pair of current collectors 500 (positive and negative sides), a first electrode 600, and a second electrode 700. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but this is not shown in the illustration. There are no particular restrictions on the type of electrolyte, as long as it does not impair the performance of the energy storage element 10, and various types can be selected. In addition to the above components, spacers may be placed to the side or below the first electrode body 600 and the second electrode body 700, insulating tape may be used to fix (bundle) the first electrode body 600 and the second electrode body 700, and insulating film may be used to enclose the first electrode body 600 and the second electrode body 700, etc.

[0029] The container 100 is a rectangular parallelepiped (square or box-shaped) case having a container body 110 with an opening formed therein and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 100. The container body 110 has a pair of flat, rectangular long sidewalls 111 on both sides (long sides) in the Y-axis direction, a pair of flat, rectangular short sidewalls 112 on both sides (short sides) in the X-axis direction, and a flat, rectangular bottom wall 113 on the Z-axis negative side. The lid 120 is a rectangular plate-shaped member extending in the X-axis direction that constitutes the lid of the container 100 and is positioned in the Z-axis positive direction of the container body 110. The lid 120 is provided with a gas discharge valve 121 for releasing pressure when the pressure inside the container 100 rises excessively, and an injection section 122 for injecting electrolyte into the container 100, etc.

[0030] With this configuration, the container 100 is sealed inside the container body 110 by joining the container body 110 and the lid 120 by welding or the like after housing the first electrode body 600 and the second electrode body 700 inside the container body 110. The material of the container 100 (container body 110 and lid 120) is not particularly limited, and weldable metals such as stainless steel, aluminum, aluminum alloy, iron, and plated steel sheet can be used, but resin can also be used.

[0031] The first electrode body 600 and the second electrode body 700 are energy storage elements (power generation elements) that can store electricity, each comprising a positive electrode plate, a negative electrode plate, and a separator. Specifically, the first electrode body 600 and the second electrode body 700 are so-called horizontally wound electrode bodies that are oval-shaped when viewed from the Z-axis direction, formed by winding layers of material arranged so that a separator is sandwiched between the positive electrode plate and the negative electrode plate.

[0032] Specifically, in the first electrode body 600, multiple tabs of the positive electrode plate are stacked to form the first positive electrode tab 620, which is a tab bundle on the positive electrode side, and multiple tabs of the negative electrode plate are stacked to form the first negative electrode tab 630, which is a tab bundle on the negative electrode side. In other words, the first electrode body 600 has a first electrode body main body portion 610 and tabs that protrude in the positive Z-axis direction from a part of the first electrode body main body portion 610, which are the first positive electrode tab 620 and the first negative electrode tab 630, which are tabs on the positive electrode side and negative electrode side, respectively. Similarly, in the second electrode body 700, multiple tabs of the positive electrode plate are stacked to form the second positive electrode tab 720, which is a tab bundle on the positive electrode side, and multiple tabs of the negative electrode plate are stacked to form the second negative electrode tab 730, which is a tab bundle on the negative electrode side. In other words, the second electrode body 700 has a second electrode body main body portion 710 and tabs that protrude in the positive Z-axis direction from a part of the second electrode body main body portion 710, and are the second positive electrode tab 720 and the second negative electrode tab 730, which are the positive electrode side and negative electrode side tabs, respectively. A detailed explanation of the configuration of the first electrode body 600 and the second electrode body 700 will be given later.

[0033] The electrode terminals 200 are terminal members (positive and negative terminals) that are electrically connected to the first electrode body 600 and the second electrode body 700 via the current collector 500. In other words, the electrode terminals 200 are metallic members that lead the electricity stored in the first electrode body 600 and the second electrode body 700 to the external space of the energy storage element 10, and also introduce electricity into the internal space of the energy storage element 10 in order to store electricity in the first electrode body 600 and the second electrode body 700. The electrode terminals 200 are made of a conductive material such as aluminum, aluminum alloy, copper, or copper alloy. The electrode terminals 200 are connected (joined) to the current collector 500 by crimping or the like, and are attached to the cover body 120.

[0034] Specifically, the electrode terminal 200 has a shaft portion 201 (rivet portion) extending downward (in the negative Z-axis direction). The shaft portion 201 is inserted into the through hole 301 of the upper gasket 300, the through hole 123 of the cover 120, the through hole 401 of the lower gasket 400, and the through hole 501 of the current collector 500, and then crimped. In this way, the electrode terminal 200 is fixed to the cover 120 together with the upper gasket 300, the lower gasket 400, and the current collector 500. The method of connecting (joining) the electrode terminal 200 and the current collector 500 is not limited to crimping, and welding methods such as ultrasonic welding, laser welding or resistance welding, or mechanical joining other than crimping, such as screw fastening, may also be used.

[0035] The current collector 500 is a flat, rectangular current collector (positive electrode current collector and negative electrode current collector) that electrically connects the first electrode body 600 and the second electrode body 700 to the electrode terminal 200. Specifically, the positive electrode current collector 500 is connected (joined) to the first positive electrode tab 620 of the first electrode body 600 and the second positive electrode tab 720 of the second electrode body 700 by welding or the like, and is also joined to the positive electrode terminal 200 by crimping or the like, as described above. The negative electrode current collector 500 is connected (joined) to the first negative electrode tab 630 of the first electrode body 600 and the second negative electrode tab 730 of the second electrode body 700 by welding or the like, and is also joined to the negative electrode terminal 200 by crimping or the like, as described above.

[0036] The material of the current collector 500 is not particularly limited, but the current collector 500 on the positive electrode side is made of a conductive material such as aluminum or an aluminum alloy, and the current collector 500 on the negative electrode side is made of a conductive material such as copper or a copper alloy. Any welding method may be used to connect (join) the current collector 500 to the first positive electrode tab 620 and the second positive electrode tab 720 or the first negative electrode tab 630 and the second negative electrode tab 730, such as ultrasonic welding, laser welding or resistance welding, or mechanical joining such as crimping or screw fastening may be used.

[0037] The upper gasket 300 is a flat, electrically insulating sealing member positioned between the lid 120 of the container 100 and the electrode terminal 200. The lower gasket 400 is a flat, electrically insulating sealing member positioned between the lid 120 and the current collector 500. The upper gasket 300 and the lower gasket 400 are formed from electrically insulating resins such as polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetherether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS resin, or composite materials thereof.

[0038] [2. Description of the configuration of the first electrode body 600 and the second electrode body 700] Next, the configurations of the first electrode body 600 and the second electrode body 700 will be described in detail. Figure 3 is a perspective view showing the configurations of the first electrode body 600 and the second electrode body 700 according to this embodiment. Since the first electrode body 600 and the second electrode body 700 have similar configurations, Figure 3 shows the configurations of the first electrode body 600 and the second electrode body 700 using the same figure. Specifically, Figure 3(a) shows the configuration of the first electrode body 600 (or the second electrode body 700) in a partially unwound state, and Figure 3(b) shows the configuration of the first electrode body 600 (or the second electrode body 700) after winding.

[0039] As described above, the first electrode body 600 and the second electrode body 700 have similar configurations. Therefore, the following description will focus on the configuration of the first electrode body 600, and the description of the configuration of the second electrode body 700 will be simplified or omitted. As shown in Figure 3(a), the first electrode body 600 has first electrode plates 640 and 650 and first separators 661 and 662, and is formed by alternately stacking and winding the first electrode plates 640 and 650 and the first separators 661 and 662. In this embodiment, the first electrode plate 640 is the positive electrode plate, and the first electrode plate 650 is the negative electrode plate. In other words, the first electrode body 600 is formed by stacking and winding the first electrode plate 640 on the positive side, the first separator 661, the first electrode plate 650 on the negative side, and the first separator 662 in this order. In this embodiment, the negative electrode first electrode plate 650 is positioned at the innermost circumference (innermost layer) and outermost circumference (outermost layer) of the first electrode plates 640 and 650 when they are wound together.

[0040] The first electrode plate 640 on the positive electrode side is an electrode plate in which a positive electrode active material layer is formed on the surface of a positive electrode base layer, which is a long, strip-shaped metal foil made of aluminum or an aluminum alloy. The first electrode plate 650 on the negative electrode side is an electrode plate in which a negative electrode active material layer is formed on the surface of a negative electrode base layer, which is a long, strip-shaped metal foil made of copper or a copper alloy. As the positive electrode base layer and the negative electrode base layer, any known material that is stable against oxidation-reduction reactions during charging and discharging can be used as appropriate, such as nickel, iron, stainless steel, titanium, calcined carbon, conductive polymer, conductive glass, Al-Cd alloy, etc. As the positive electrode active material used in the positive electrode active material layer and the negative electrode active material used in the negative electrode active material layer, any known material that is capable of intercalating and deintercalating lithium ions can be used as appropriate.

[0041] As positive electrode active materials, polyanionic compounds such as LiMPO4, LiMSiO4, LiMBO3 (where M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, LiMn2O4, and LiMn 1.5 Ni 0.5Spinel-type lithium manganese oxides such as O4, lithium transition metal oxides such as LiMO2 (where M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) can be used. As negative electrode active materials, lithium metals, lithium alloys (lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as Wood's alloys), alloys capable of intercalating and deintercalating lithium, carbon materials (e.g., graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature calcined carbon, amorphous carbon, etc.), silicon oxides, metal oxides, lithium metal oxides (Li4Ti5O 12 Examples include polyphosphate compounds, or compounds of transition metals and group 14 to 16 elements, such as Co3O4 and Fe2P, which are generally called conversion negative electrodes.

[0042] The first separators 661 and 662 are microporous sheets made of resin. Any known material can be used for the first separators 661 and 662, as long as it does not impair the performance of the energy storage element 10. As the first separators 661 and 662, woven fabrics, nonwoven fabrics, synthetic resin microporous membranes made of polyolefin resins such as polyethylene, which are insoluble in organic solvents, can be used.

[0043] The first electrode plate 640 has a plurality of rectangular tabs 641 protruding in the Z-axis direction at its Z-axis positive end, and the plurality of tabs 641 are arranged in a stacked state in the Y-axis direction. Similarly, the first electrode plate 650 has a plurality of rectangular tabs 651 protruding in the Z-axis direction at its Z-axis positive end, and the plurality of tabs 651 are arranged in a stacked state in the Y-axis direction. Tabs 641 and 651 are portions where the active material layer is not formed and the base material layer is exposed. The shape of tabs 641 and 651 is not particularly limited.

[0044] As shown in Figure 3(b), a plurality of stacked tabs 641 are bundled together to form a first positive electrode tab 620 that extends in the positive Z-axis direction. Similarly, a plurality of stacked tabs 651 are bundled together to form a first negative electrode tab 630 that extends in the positive Z-axis direction. In this embodiment, the first positive electrode tab 620 and the first negative electrode tab 630 are positioned to protrude in the positive Z-axis direction from a part of the first electrode body flat portion 611, which will be described later. These first positive electrode tab 620 and the first negative electrode tab 630 are joined to the positive Y-axis direction surface of the current collector 500, which is facing it in the Y-axis direction, and then bent in the positive Y-axis direction together with the current collector 500.

[0045] The first electrode body main body 610 is the part that constitutes the main body of the first electrode body 600, and specifically, it is the part of the first electrode body 600 other than the first positive electrode tab 620 and the first negative electrode tab 630. In other words, the first electrode body main body 610 is an elongated cylindrical or oval-shaped part formed by winding the active material layers of the first electrode plates 640 and 650 with the first separators 661 and 662. As a result, the first electrode body main body 610 has a pair of first electrode body flat sections 611 and 612 on both sides in the Y-axis direction, and a pair of first electrode body curved sections 613 and 614 on both sides in the X-axis direction.

[0046] The first electrode body flat portion 611 is a flat and rectangular portion that connects a pair of first electrode body curved portions 613 and 614, extending parallel to the XZ plane oriented in the negative Y-axis direction, and is positioned opposite the long side wall portion 111 of the container body 110 in the negative Y-axis direction. The first electrode body flat portion 612 is a flat and rectangular portion that connects a pair of first electrode body curved portions 613 and 614, extending parallel to the XZ plane oriented in the positive Y-axis direction, and is positioned opposite the second electrode body 700. The first electrode body curved portion 613 is a curved portion that curves in a semicircular arc shape so as to project in the negative X-axis direction when viewed from the Z-axis direction, and extends in the Z-axis direction, and is positioned opposite the short side wall portion 112 of the container body 110 in the negative X-axis direction. The first electrode body curved portion 614 is curved in a semicircular arc shape so as to protrude in the positive X-axis direction when viewed from the Z-axis direction, and is a curved portion that extends in the Z-axis direction, and is positioned opposite the short side wall portion 112 of the container body 110 in the positive X-axis direction.

[0047] Similarly, the second electrode body 700 also has second electrode plates 740 and 750 and second separators 761 and 762, and is formed by alternately stacking and winding the second electrode plates 740 and 750 and the second separators 761 and 762. In this embodiment, the second electrode plate 740 is a positive electrode plate, and the second electrode plate 750 is a negative electrode plate. The second electrode plate 740 has tabs 741, and the second electrode plate 750 has tabs 751. Multiple tabs 741 are bundled together to form a second positive electrode tab 720, and multiple tabs 751 are bundled together to form a second negative electrode tab 730.

[0048] In this embodiment, the second positive electrode tab 720 is positioned in a location corresponding to the first negative electrode tab 630, and the second negative electrode tab 730 is positioned in a location corresponding to the first positive electrode tab 620. In other words, the second positive electrode tab 720 and the second negative electrode tab 730 are positioned in the opposite locations to the first positive electrode tab 620 and the first negative electrode tab 630. To put it another way, the second electrode plate 740 has a tab 741 in a location corresponding to the tab 651 of the first electrode plate 650, and the second electrode plate 750 has a tab 751 in a location corresponding to the tab 641 of the first electrode plate 640. It can also be said that the second electrode plate 740 is positioned in a location corresponding to the first electrode plate 650, and the second electrode plate 750 is positioned in a location corresponding to the first electrode plate 640 (the positions of the positive and negative electrode plates are reversed between the first electrode body 600 and the second electrode body 700). However, the negative electrode plate 750, like the first electrode plate 650, is positioned at the innermost circumference (innermost layer) and outermost circumference (outermost layer) of the second electrode plates 740 and 750 when they are wound together. In Figure 3, the second electrode body 700 is shown with the stacking order of the positive and negative electrode plates reversed compared to the first electrode body 600. However, the positions of the tabs on the positive and negative electrode plates may be reversed compared to the first electrode body 600, and the positive and negative electrode plates may be wound together in the same stacking order as the first electrode body 600.

[0049] The second electrode body 700 has a second electrode body main body portion 710 which has a pair of second electrode body flat portions 711 and 712 on both sides in the Y-axis direction and a pair of second electrode body curved portions 713 and 714 on both sides in the X-axis direction. In this embodiment, the second electrode body flat portion 711 is positioned at a location corresponding to the first electrode body flat portion 612 of the first electrode body 600, and the second electrode body flat portion 712 is positioned at a location corresponding to the first electrode body flat portion 611 of the first electrode body 600. In other words, the second positive electrode tab 720 and the second negative electrode tab 730 are positioned protruding in the positive Z-axis direction from a part of the second electrode body flat portion 712. The second electrode body curved portion 713 is positioned at a location corresponding to the first electrode body curved portion 614 of the first electrode body 600, and the second electrode body curved portion 714 is positioned at a location corresponding to the first electrode body curved portion 613 of the first electrode body 600.

[0050] As shown in Figure 2, the second electrode body 700 is positioned in the positive Y-axis direction of the first electrode body 600, rotated 180° around the Z-axis from the state shown in Figure 3(b). As a result, the flat portion 711 of the second electrode body is positioned opposite the first electrode body 600, facing the negative Y-axis direction. The flat portion 712 of the second electrode body is positioned opposite the long side wall portion 111 of the container body 110 in the positive Y-axis direction, facing the positive Y-axis direction. The curved portion 713 of the second electrode body is positioned opposite the short side wall portion 112 of the container body 110 in the negative X-axis direction, projecting in the negative X-axis direction. The curved portion 714 of the second electrode body is positioned opposite the short side wall portion 112 of the container body 110 in the positive X-axis direction, projecting in the positive X-axis direction.

[0051] Thus, at least one of the first electrode body portion 610 and the second electrode body portion 710 has a pair of curved portions formed by winding at least one of the first electrode plates 640, 650 and the second electrode plates 740, 750, and a flat portion connecting the pair of curved portions. In this embodiment, both the first electrode body portion 610 and the second electrode body portion 710 have a pair of curved portions formed by winding the first electrode plates 640, 650 and the second electrode plates 740, 750, and a flat portion connecting the pair of curved portions.

[0052] [3. Explanation of the details and positional relationship of the first electrode 600 and the second electrode 700] Next, a more detailed explanation of the first electrode body 600 and the second electrode body 700, and their positional relationship will be provided. Figure 4 is a top view showing the configuration of the first electrode body 600 according to this embodiment. Figure 5 is a top view showing the configuration of the second electrode body 700 according to this embodiment. Figure 6 is a top view showing the positional relationship between the first electrode body 600 and the second electrode body 700 according to this embodiment. Specifically, Figures 4 and 5 are views of the first electrode body 600 and the second electrode body 700 from the Z-axis positive direction, and Figure 6 is a view from the Z-axis positive direction of the configuration when the first electrode body 600 shown in Figure 4 and the second electrode body 700 shown in Figure 5 are assembled.

[0053] In the first electrode body 600, the first electrode plates 640 and 650 are wound together, so although the negative electrode side first electrode plate 650 is slightly longer in the winding direction than the positive electrode side first electrode plate 640, they have generally similar shapes when viewed from the positive Z-axis direction. For this reason, in Figures 4 and 6, the illustration of one of the first electrode plates 640 and 650 of the first electrode body 600 (e.g., the first electrode plate 640) and the first separators 661 and 662 is omitted, and the other electrode plate (e.g., the first electrode plate 650) is shown wound. Similarly, in Figures 5 and 6, the illustration of one of the second electrode plates 740 and 750 (e.g., the second electrode plate 740) and the second separators 761 and 762 is omitted, and the other electrode plate (e.g., the second electrode plate 750) is shown wound. Figures 4 to 6 show simplified diagrams with reduced winding counts for the first electrode plate 650 (or 640) and the second electrode plate 750 (or 740).

[0054] As shown in Figure 4, in the first electrode body 600, the first electrode body main body 610 has a first electrode plate starting end 612a and a first electrode plate ending end 612b. The first electrode plate starting end 612a is the starting portion of the winding of the first electrode plate 650 (or 640), and in this embodiment, it is located at the Y-axis negative end and in the X-axis center of the first electrode body flat portion 612. The first electrode plate starting end 612a is located at the innermost circumference (innermost layer) of the first electrode plate 650 (or 640) and is the tip portion of the electrode plate extending in the X-axis positive direction from the first electrode body curved portion 613.

[0055] The first electrode plate end portion 612b is the winding end portion of the first electrode plate 650 (or 640), and in this embodiment, it is located at the Y-axis positive end and in the X-axis center of the first electrode body flat portion 612. The first electrode plate end portion 612b is located on the outermost periphery (outermost layer) of the first electrode plate 650 (or 640) and is the tip portion of the electrode plate extending in the X-axis negative direction from the first electrode body curved portion 614. The first electrode plate end portion 612b is located in the X-axis positive direction more than the first electrode plate start portion 612a. In other words, the first electrode plate end portion 612b is located in a position that does not overlap with the first electrode plate start portion 612a when viewed from the Y-axis direction.

[0056] As shown in Figure 5, in the second electrode body 700, the second electrode body main body portion 710 has a second electrode plate starting end portion 711a and a second electrode plate ending end portion 711b. The second electrode plate starting end portion 711a is the starting portion of the winding of the second electrode plate 750 (or 740), and in this embodiment, it is located at the Y-axis positive end and in the X-axis center of the second electrode body flat portion 711. The second electrode plate starting end portion 711a is located at the innermost circumference (innermost layer) of the second electrode plate 750 (or 740) and is the tip portion of the electrode plate extending in the X-axis negative direction from the second electrode body curved portion 714.

[0057] The second electrode plate end portion 711b is the winding end portion of the second electrode plate 750 (or 740), and in this embodiment, it is located at the Y-axis negative end and in the X-axis center of the second electrode body flat portion 711. The second electrode plate end portion 711b is located on the outermost periphery (outermost layer) of the second electrode plate 750 (or 740) and is the tip portion of the electrode plate extending in the X-axis positive direction from the second electrode body curved portion 713. The second electrode plate end portion 711b is located in the X-axis negative direction more than the second electrode plate start portion 711a. In other words, the second electrode plate end portion 711b is located in a position that does not overlap with the second electrode plate start portion 711a when viewed from the Y-axis direction.

[0058] Thus, at least one of the first electrode plate end portion 612b and the second electrode plate end portion 711b is located on the flat portion of the electrode body. In this embodiment, both the first electrode plate end portion 612b and the second electrode plate end portion 711b are located on the flat portion of the electrode body (first electrode body flat portion 612 and second electrode body flat portion 711). Similarly, at least one of the first electrode plate start portion 612a and the second electrode plate start portion 711a is located on the flat portion of the electrode body. In this embodiment, both the first electrode plate start portion 612a and the second electrode plate start portion 711a are located on the flat portion of the electrode body (first electrode body flat portion 612 and second electrode body flat portion 711).

[0059] In the configuration described above, as shown in Figure 6, the first electrode plate end portion 612b of the first electrode body 600 is positioned opposite the second electrode body main body portion 710 of the second electrode body 700 (opposite the second electrode body flat portion 711). Specifically, the first electrode plate end portion 612b extends to the central part of the portion of the first electrode body main body portion 610 that faces the second electrode body main body portion 710. Since the portion of the first electrode body main body portion 610 that faces the second electrode body main body portion 710 is the first electrode body flat portion 612, the first electrode plate end portion 612b extends to the central part of the first electrode body flat portion 612 in the X-axis direction.

[0060] The second electrode plate end portion 711b of the second electrode body 700 is positioned opposite the first electrode body main body portion 610 of the first electrode body 600 (opposite the first electrode body flat portion 612). Specifically, the second electrode plate end portion 711b extends to the central part of the portion of the second electrode body main body portion 710 that faces the first electrode body main body portion 610. Since the portion of the second electrode body main body portion 710 that faces the first electrode body main body portion 610 is the second electrode body flat portion 711, the second electrode plate end portion 711b extends to the central part of the second electrode body flat portion 711 in the X-axis direction.

[0061] As a result, the first electrode plate end portion 612b and the second electrode plate end portion 711b are positioned opposite each other in the X-axis direction, with their tips facing each other. In other words, the first electrode plate end portion 612b and the second electrode plate end portion 711b are positioned projecting in opposite directions when viewed from the direction of alignment of the first electrode body 600 and the second electrode body 700 (Y-axis direction). To put it another way, the first electrode plate end portion 612b extends toward the second electrode plate end portion 711b at the portion of the first electrode body body 610 that faces the second electrode body body 710. The second electrode plate end portion 711b extends toward the first electrode plate end portion 612b at the portion of the second electrode body body 710 that faces the first electrode body body 610. The first electrode plate end portion 612b and the second electrode plate end portion 711b are positioned so as not to overlap when viewed from the direction of alignment of the first electrode body 600 and the second electrode body 700 (Y-axis direction). In this embodiment, the first electrode plate end portion 612b and the second electrode plate end portion 711b are spaced apart in the X-axis direction when viewed from the Y-axis direction, but they may be spaced apart in the X-axis direction. Specifically, the distance between the first electrode plate end portion 612b and the second electrode plate end portion 711b is preferably 50% or less, more preferably 30% or less, and even more preferably 10% or less, of the length of the first electrode body main portion 610 or the second electrode body main portion 710 in the X-axis direction.

[0062] In this embodiment, the first electrode plate end portion 612b and the second electrode plate end portion 711b are positioned so as not to overlap beyond each other's ends, but rather in front of each other's ends. In other words, the first electrode plate end portion 612b is positioned so as not to overlap with the second electrode plate end portion 711b in the X-axis direction, but rather in front of the second electrode plate end portion 711b. Similarly, the second electrode plate end portion 711b is positioned so as not to overlap with the first electrode plate end portion 612b in the X-axis direction, but rather in front of the first electrode plate end portion 612b.

[0063] The first electrode plate starting end 612a of the first electrode body 600 and the second electrode plate starting end 711a of the second electrode body 700 are positioned opposite each other in the X-axis direction when viewed from the Y-axis direction. In other words, the first electrode plate starting end 612a and the second electrode plate starting end 711a are positioned so that they protrude in opposite directions when viewed from the direction in which the first electrode body 600 and the second electrode body 700 are aligned (Y-axis direction), and do not overlap. In this embodiment, the first electrode plate starting end 612a and the second electrode plate starting end 711a are spaced apart in the X-axis direction when viewed from the Y-axis direction, but they may be positioned without a gap in the X-axis direction. Similarly, the first electrode plate starting end 612a and the first electrode plate ending end 612b are spaced apart in the X-axis direction when viewed from the Y-axis direction, but they may be positioned without a gap in the X-axis direction. The starting end portion 711a and the ending end portion 711b of the second electrode plate are arranged with a gap in the X-axis direction when viewed from the Y-axis direction, but they may also be arranged without a gap in the X-axis direction.

[0064] Specifically, the distance between the first electrode plate starting end 612a and the second electrode plate starting end 711a is preferably 50% or less, more preferably 30% or less, and even more preferably 10% or less, of the length of the first electrode body main portion 610 or the second electrode body main portion 710 in the X-axis direction. The same applies to the distance between the first electrode plate starting end 612a and the first electrode plate ending end 612b, and the distance between the second electrode plate starting end 711a and the second electrode plate ending end 711b.

[0065] The configuration and positional relationship of the first separators 661 and 662, and the second separators 761 and 762, are not particularly limited, but they can have the same configuration and positional relationship as the second electrode plate 750 (or 740) and the second electrode plate 750 (or 740).

[0066] As described above, the first electrode plate start end 612a and the first electrode plate end end 612b are arranged on the first electrode body flat portion 612 facing the second electrode body 700, while the first positive electrode tab 620 and the first negative electrode tab 630 are arranged on the first electrode body flat portion 611 opposite to the second electrode body 700. The second electrode plate start end 711a and the second electrode plate end end 711b are arranged on the second electrode body flat portion 711 facing the first electrode body 600, while the second positive electrode tab 720 and the second negative electrode tab 730 are arranged on the second electrode body flat portion 712 opposite to the first electrode body 600.

[0067] In other words, at least one of the first positive electrode tab 620 and the first negative electrode tab 630 is positioned to protrude from a portion of the first electrode body body 610 that is on the opposite side of the second electrode body body 710 (first electrode body flat portion 611) rather than the portion of the first electrode body body 610 that is facing the second electrode body body 710 (first electrode body flat portion 612). Of the second positive electrode tab 720 and the second negative electrode tab 730, the tab with the same polarity as at least one of the first positive electrode tab 620 and the first negative electrode tab 630 is positioned to protrude from a portion of the second electrode body body 710 that is on the opposite side of the first electrode body body 610 (second electrode body flat portion 712) rather than the portion of the second electrode body body 610 that is facing the first electrode body body 610 (second electrode body flat portion 711). In this embodiment, both the first positive electrode tab 620 and the first negative electrode tab 630 are positioned to protrude from a portion of the first electrode body body 611 that is on the opposite side of the second electrode body body 710. Both the second positive electrode tab 720 and the second negative electrode tab 730 are positioned to protrude from a portion of the second electrode body flat portion 712 on the side of the second electrode body main body portion 710 that is opposite to the first electrode body main body portion 610.

[0068] A first positive electrode tab 620 is positioned at the end of the first electrode body flat portion 611 in the negative X-axis direction, and a first negative electrode tab 630 is positioned at the end of the first electrode body flat portion 611 in the positive X-axis direction. A second positive electrode tab 720 is positioned at the end of the second electrode body flat portion 712 in the negative X-axis direction, and a second negative electrode tab 730 is positioned at the end of the second electrode body flat portion 712 in the positive X-axis direction. With this configuration, the direction from the first positive electrode tab 620 to the first negative electrode tab 630 and the direction from the second positive electrode tab 720 to the second negative electrode tab 730 are the same. In other words, the direction from the first positive electrode tab 620 to the first negative electrode tab 630 and the direction from the second positive electrode tab 720 to the second negative electrode tab 730 are not only parallel to the X-axis direction, but are also in the same direction (same orientation) as one direction in the X-axis direction (in this embodiment, the positive X-axis direction).

[0069] In other words, the first positive electrode tab 620 and the second positive electrode tab 720 are positioned in the same direction (negative X-axis direction) relative to the first negative electrode tab 630 and the second negative electrode tab 730. That is, the first positive electrode tab 620 and the second positive electrode tab 720 are positioned on the same side of the X-axis relative to the center position of the first electrode body 600 and the center position of the second electrode body 700. The first negative electrode tab 630 and the second negative electrode tab 730 are positioned on the opposite side of the X-axis relative to the center position of the first electrode body 600 and the center position of the second electrode body 700 from the first positive electrode tab 620 and the second positive electrode tab 720. Specifically, the first positive electrode tab 620 and the second positive electrode tab 720 are positioned in overlapping positions when viewed from the Y-axis direction, and the first negative electrode tab 630 and the second negative electrode tab 730 are positioned in overlapping positions when viewed from the Y-axis direction. In this embodiment, the first positive electrode tab 620 and the second positive electrode tab 720 are positioned at the same location in the X-axis direction, and the first negative electrode tab 630 and the second negative electrode tab 730 are positioned at the same location in the X-axis direction.

[0070] [4. Explanation of Effects] As described above, according to the energy storage element 10 according to the embodiment of the present invention, the first electrode body 600 formed by winding the first electrode plates 640 and 650 has a first electrode body main body portion 610, a first positive electrode tab 620, and a first negative electrode tab 630. The second electrode body 700 formed by winding the second electrode plates 740 and 750 has a second electrode body main body portion 710, a second positive electrode tab 720, and a second negative electrode tab 730. The first electrode plate end portion 612b of the first electrode body main body portion 610, which faces the second electrode body main body portion 710, and the second electrode plate end portion 711b of the second electrode body main body portion 710, which faces the first electrode body main body portion 610, are positioned so as not to overlap. Thus, the first electrode plate end portion 612b of the first electrode body 610 is positioned opposite the second electrode body 710, and the second electrode plate end portion 711b of the second electrode body 710 is positioned opposite the first electrode body 610 and in a position that does not overlap with the first electrode plate end portion 612b. This suppresses the creation of wasted space between the first electrode body 600 and the second electrode body 700 (between the first electrode body 610 and the second electrode body 710), thereby enabling miniaturization or increased capacity of the energy storage element 10. However, the statement that the first electrode plate end portion 612b and the second electrode plate end portion 711b are positioned in a position that does not overlap with each other does not include the statement that the first electrode plate end portion 612b and the second electrode plate end portion 711b are positioned in a position that does not overlap beyond each other's ends.

[0071] In other words, when the first electrode plate end portion 612b of the first electrode body 610 is positioned facing the inner surface of the second electrode body 710 or the container 100, there is wasted space between the portion of the first electrode body 610 where the first electrode plate end portion 612b is not located and the inner surface of the second electrode body 710 or the container 100. For this reason, the first electrode plate end portion 612b is positioned facing the second electrode body 710, and the second electrode plate end portion 711b is positioned facing the first electrode body 610 and in a position that does not overlap with the first electrode plate end portion 612b. As a result, the second electrode plate end portion 711b can be positioned in the portion of the first electrode body 610 where the first electrode plate end portion 612b is not located, thereby suppressing the occurrence of the wasted space and enabling miniaturization or increased capacity of the energy storage element 10.

[0072] When the first electrode plate end portion 612b and the second electrode plate end portion 711b are arranged without any gap in the X-axis direction when viewed from the Y-axis direction, the length of the electrode plates can be increased compared to when they are arranged with a gap between them. In this case, the space between the first electrode body 600 and the second electrode body 700 can be effectively utilized, and the storage element 10 can be made smaller or have a higher capacity.

[0073] The configuration in which the first electrode plate end portion 612b of the first electrode body 600 is positioned opposite the second electrode body main body 710, and the second electrode plate end portion 711b of the second electrode body 700 is positioned opposite the first electrode body main body 610, can be achieved by rotating one of the two identical electrode bodies by 180°. The above configuration can be achieved by defining the electrode body obtained by rotating the first electrode body 600 by 180° as the second electrode body 700, and defining the first electrode plate end portion 612b of the first electrode body 600 obtained by rotating by 180° as the second electrode plate end portion 711b. However, in this case, the first positive electrode tab 620 and the second positive electrode tab 720 are positioned in opposite directions to the first negative electrode tab 630 and the second negative electrode tab 730, making it difficult to connect tabs of the same polarity to a single current collector 500. Therefore, even if the first electrode plate end portion 612b and the second electrode plate end portion 711b are arranged as described above, the direction from the first positive electrode tab 620 toward the first negative electrode tab 630 and the direction from the second positive electrode tab 720 toward the second negative electrode tab 730 are arranged in the same direction. As a result, the first positive electrode tab 620 and the second positive electrode tab 720 are arranged in the same direction with respect to the first negative electrode tab 630 and the second negative electrode tab 730, so that tabs of the same polarity can be easily connected to a single current collector 500.

[0074] The configuration in which the first electrode plate end portion 612b of the first electrode body 600 is positioned opposite the second electrode body main portion 710, and the second electrode plate end portion 711b of the second electrode body 700 is positioned opposite the first electrode body main portion 610, can be achieved by positioning two identical electrode bodies in the same orientation and adjusting the length of the electrode plates. The above configuration can be achieved by adjusting the lengths of the first electrode plates 640 and 650 of the first electrode body 600 to the same length as the second electrode plates 740 and 750 without rotating the first electrode body 600, and defining it as the second electrode body 700. This configuration can be achieved by positioning two electrode bodies in which the electrode plates are wound in the same orientation from the same starting position, the direction from the positive electrode tab to the negative electrode tab is the same (the position of the positive electrode tab and the negative electrode tab are the same), and the lengths of the electrode plates are different, by adjusting the length of the electrode plates (the end position of the electrode plates). This makes it easy to suppress the occurrence of wasted space between the first electrode body 600 and the second electrode body 700 (between the main body portion 610 of the first electrode body and the main body portion 710 of the second electrode body), thus making it easy to miniaturize or increase the capacity of the energy storage element 10.

[0075] However, in this case, the tabs of either the first electrode body 600 or the second electrode body 700 will be positioned on the opposite side of the other electrode body. In other words, if the first electrode body 600 is defined as the second electrode body 700 without being rotated, the first positive electrode tab 620 and the first negative electrode tab 630 protrude from the flat portion 611 of the first electrode body, and consequently, the second positive electrode tab 720 and the second negative electrode tab 730 protrude from the flat portion 711 of the second electrode body. As a result, the distance between tabs of the same polarity on the first electrode body 600 and the second electrode body 700 becomes shorter, and the tabs become densely packed, which may result in wasted space or make it difficult to connect to the current collector 500. Therefore, at least one tab of the first electrode body 600 is positioned to protrude from the part of the first electrode body main body 610 opposite to the part of the second electrode body main body 710, and a tab of the second electrode body 700 having the same polarity as the tab in question is positioned to protrude from the part of the second electrode body main body 710 opposite to the part of the second electrode body main body 710. In other words, tabs of the same polarity on the first electrode body 600 and the second electrode body 700 are positioned on opposite sides of the parts of their respective electrode body main bodies that face each other. As a result, tabs of the same polarity on the first electrode body 600 and the second electrode body 700 are positioned at separate locations, which helps to disperse the tabs, prevent wasted space, and make the tabs easier to bend, allowing for easy connection to the current collector 500.

[0076] At least one of the electrode plate end portions, the first electrode plate end portion 612b and the second electrode plate end portion 711b, is positioned on the flat portion of at least one of the electrode body main portions, the first electrode body main portion 610 and the second electrode body main portion 710. This allows the fixing position of the electrode plate end portion on the electrode body to be on the flat portion, so that the electrode plate end portion can be easily fixed to the electrode body with tape or the like. In this embodiment, flat portions (first electrode body flat portion 612 and second electrode body flat portion 711) are formed on both the first electrode body main portion 610 and the second electrode body main portion 710. Therefore, the electrode plate end portion can be sandwiched between the flat portions (first electrode body flat portion 612 and second electrode body flat portion 711) of both the first electrode body main portion 610 and the second electrode body main portion 710, so that the electrode plate end portion can be easily fixed.

[0077] By arranging both the first electrode plate end portion 612b and the second electrode plate end portion 711b so that they extend toward each other in the first electrode body portion 610 and the second electrode body portion 710, the overall length of the first electrode plates 640 and 650 and the second electrode plates 740 and 750 can be increased. This allows for effective use of the space between the first electrode body 600 and the second electrode body 700, and increases the capacity of the first electrode body 600 and the second electrode body 700, thereby enabling miniaturization or increased capacity of the energy storage element 10. Specifically, the distance between the first electrode plate end portion 612b and the second electrode plate end portion 711b is preferably 50% or less, more preferably 30% or less, and even more preferably 10% or less of the length of the first electrode body portion 610 or the second electrode body portion 710 in the X-axis direction. The closer the distance between the first electrode plate end portion 612b and the second electrode plate end portion 711b, the more effectively the space between the first electrode body 600 and the second electrode body 700 can be utilized, and the greater the increase in the capacitance of the first electrode body 600 and the second electrode body 700 can be achieved.

[0078] The first electrode plate starting end 612a of the first electrode body 610 and the second electrode plate starting end 711a of the second electrode body 710 are positioned so as not to overlap when viewed from the direction of alignment (Y-axis direction) of the first electrode body 600 and the second electrode body 700. This reduces the overlap between the first electrode plate 650 (or 640) and the second electrode plate 750 (or 740), thereby enabling miniaturization or increased capacity of the energy storage element 10.

[0079] The above configuration can be applied to both the first electrode plates 640 and 650. However, since the negative electrode first electrode plate 650 is positioned at the innermost circumference (innermost layer) and outermost circumference (outermost layer) of the first electrode plates 640 and 650, applying it to the first electrode plate 650 enhances the above-mentioned effects more effectively than applying it to the first electrode plate 640. Applying it to both the first electrode plates 640 and 650 enhances the above-mentioned effects more effectively than applying it to just one of them. For the first separators 661 and 662, a high level of effect cannot be obtained due to their thin thickness, but the above-mentioned effects can be obtained by using the same configuration as the first electrode plate 650 (or 640) described above. The same applies to the second electrode plates 740 and 750, and the second separators 761 and 762.

[0080] [5 Explanation of variations] Although an embodiment of the energy storage element 10 according to the present invention has been described above, the present invention is not limited to this embodiment. The embodiments disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims.

[0081] In the above embodiment, the arrangement positions of the tabs of the first electrode body 600 and the second electrode body 700 (first positive electrode tab 620 and first negative electrode tab 630, and second positive electrode tab 720 and second negative electrode tab 730) are not particularly limited. Specifically, they are as follows.

[0082] In the above embodiment, at least one of the first positive electrode tab 620 and the first negative electrode tab 630 may be positioned to protrude from the first electrode body flat portion 612, and at least one of the second positive electrode tab 720 and the second negative electrode tab 730 may be positioned to protrude from the second electrode body flat portion 711. In other words, as shown in Figure 7, the first positive electrode tab 620 and the first negative electrode tab 630 may be positioned to protrude from a part of the first electrode body body portion 610 that faces the second electrode body body portion 710 (first electrode body flat portion 612). The second positive electrode tab 720 and the second negative electrode tab 730 may be positioned to protrude from a part of the second electrode body body portion 710 that faces the first electrode body body portion 610 (second electrode body flat portion 711). Figure 7 is a top view showing an example of the arrangement position of the tabs of the first electrode body 600a and the second electrode body 700a according to Modification 1 of this embodiment. Specifically, Figure 7 is a diagram corresponding to Figure 6. This modified configuration is preferable when bundling the first positive electrode tab 620 and the second positive electrode tab 720 makes it easier to connect them to the current collector 500.

[0083] In the above embodiment, the direction from the first positive electrode tab 620 to the first negative electrode tab 630 and the direction from the second positive electrode tab 720 to the second negative electrode tab 730 may be different directions. The first positive electrode tab 620 and the first negative electrode tab 630 may be positioned in opposite positions, or the second positive electrode tab 720 and the second negative electrode tab 730 may be positioned in opposite positions.

[0084] In the above embodiment, the first positive electrode tab 620 and the second positive electrode tab 720 may be positioned offset in the X-axis direction so that they do not overlap when viewed from the Y-axis direction. The same applies to the first negative electrode tab 630 and the second negative electrode tab 730. As described above, the position of the tabs of the first electrode body 600 and the second electrode body 700 is not particularly limited, and various configurations are possible.

[0085] In the above embodiment, the first electrode plate starting end 612a and the first electrode plate ending end 612b of the first electrode body 600 are positioned in the X-axis center of the first electrode body flat portion 612, and the second electrode plate starting end 711a and the second electrode plate ending end 711b of the second electrode body 700 are positioned in the X-axis center of the second electrode body flat portion 711. However, the following configuration is also acceptable.

[0086] In the above embodiment, the first electrode plate starting end may be positioned on the first electrode body flat portion 611, and the second electrode plate starting end may be positioned on the second electrode body flat portion 712. Figure 8 is a top view showing an example of the positioning of the electrode plate starting ends of the first electrode body 600b and the second electrode body 700b according to a modified example 2 of this embodiment. Specifically, Figure 8 corresponds to Figure 6. As shown in Figure 8, the first electrode plate starting end 611a is positioned in the center of the first electrode body flat portion 611 in the X-axis direction, and the second electrode plate starting end 712a is positioned in the center of the second electrode body flat portion 712 in the X-axis direction. The first electrode plate starting end 611a and the second electrode plate starting end 712a are positioned so as to protrude in opposite directions to each other and not overlap when viewed from the direction of alignment of the first electrode body 600b and the second electrode body 700b (Y-axis direction).

[0087] In the above embodiment, the first electrode plate starting end 612a may be located at the X-axis direction end of the first electrode body flat portion 612, and the second electrode plate starting end 711a may be located at the X-axis direction end of the second electrode body flat portion 711. The first electrode plate starting end 612a may be located at the X-axis negative direction end of the first electrode body flat portion 612, and the second electrode plate starting end 711a may be located at the X-axis negative direction end or the X-axis positive direction end of the second electrode body flat portion 711. The first electrode plate starting end 612a may be located at the first electrode body curved portion 613 or 614, and the second electrode plate starting end 711a may be located at the second electrode body curved portion 713 or 714. The first electrode plate starting end 612a may be located at the first electrode body curved portion 613, and the second electrode plate starting end 711a may be located at the second electrode body curved portion 713 or 714. The same applies to the first electrode plate starting end 611a and the second electrode plate starting end 712a shown in Figure 8.

[0088] In the above embodiment, the first electrode plate starting end 612a and the second electrode plate starting end 711a may be positioned to overlap when viewed from the Y-axis direction. The first electrode plate starting end 612a and the second electrode plate starting end 711a may be positioned in any other position besides the above embodiment. The same applies to the first electrode plate starting end 611a and the second electrode plate starting end 712a shown in Figure 8. Figure 9 is a top view showing an example of the arrangement positions of the electrode plate starting ends and tabs of the first electrode body 600 and the second electrode body 700c according to Modification 3 of this embodiment. Specifically, Figure 9 corresponds to Figure 6. As shown in Figure 9, the first electrode plate starting end 612a and the second electrode plate starting end 712a are positioned to overlap when viewed from the Y-axis direction. In this modification, the second positive electrode tab 720 and the second negative electrode tab 730 are positioned protruding from a part of the second electrode body body portion 710 that faces the first electrode body body portion 610 (second electrode body flat portion 711). In other words, in this modified example, the second electrode body 700c is an electrode body having the same configuration as the first electrode body 600, but with the end portion of the electrode plate wound extended to the position of the second electrode body flat portion 711. To put it another way, the first electrode body 600 and the second electrode body 700c are two electrode bodies in which the electrode plates are wound in the same direction from the same starting position, the positive electrode tab and the negative electrode tab are positioned in the same place, and the end positions of the electrode plates are different (adjusted by different lengths of electrode plates).

[0089] In the above embodiment, the first electrode plate end portion 612b may be located at the X-axis end of the first electrode body flat portion 612, and the second electrode plate end portion 711b may be located at the X-axis end of the second electrode body flat portion 711. The first electrode plate end portion 612b may be located at the X-positive end of the first electrode body flat portion 612, and the second electrode plate end portion 711b may be located at a position on the X-positive end of the second electrode body flat portion 711 that does not overlap with the first electrode plate end portion 612b when viewed from the Y-axis direction, or at the X-negative end of the second electrode body flat portion 711. The same applies when the first electrode plate end portion 612b is located at the X-negative end of the first electrode body flat portion 612.

[0090] In the above embodiment, the first electrode plate end portion 612b may be located on the first electrode body curved portion 613 or 614, and the second electrode plate end portion 711b may be located on the second electrode body curved portion 713 or 714. The first electrode plate end portion 612b may be located on the first electrode body curved portion 614 opposite the second electrode body curved portion 714. In this case, the second electrode plate end portion 711b may be located on the second electrode body curved portion 714 opposite the first electrode body curved portion 614, and in a position that does not overlap with the first electrode plate end portion 612b when viewed from the Y-axis direction, or it may be located on the second electrode body curved portion 713 opposite the first electrode body curved portion 613. The same applies when the first electrode plate end portion 612b is located on the first electrode body curved portion 613.

[0091] In the above embodiment, both the first electrode plates 640 and 650 are assumed to have the above configuration, but it is not necessary for either the first electrode plate 640 or 650 to have the above configuration. However, as described above, since the negative electrode first electrode plate 650 is positioned at the innermost circumference (innermost layer) and outermost circumference (outermost layer) of the first electrode plates 640 and 650, applying it to the first electrode plate 650 is more effective than applying it to the first electrode plate 640. For this reason, it is preferable that the first electrode plate 650 has the above configuration. It is even more preferable that both the first electrode plates 640 and 650 have the above configuration. The same applies to the second electrode plates 740 and 750.

[0092] In the above embodiment, the number of turns (number of layers) of the electrode plates of the first electrode body 600 and the second electrode body 700 is not particularly limited, and the number of turns (number of layers) of the electrode plates of the first electrode body 600 and the second electrode body 700 may be the same or different. By adjusting the number of turns of the first electrode body 600 and the second electrode body 700 and adjusting the length of the electrode plates, the above various configurations can be realized.

[0093] In the above embodiment, the first electrode body 600 and the second electrode body 700 are assumed to have an oval shape when viewed from the Z-axis direction. However, at least one of the first electrode body 600 and the second electrode body 700 may have an elliptical or circular shape when viewed from the Z-axis direction, and the shape is not particularly limited. In other words, at least one of the first electrode body main body 610 and the second electrode body main body 710 may not have a flat portion. In an electrode body without a flat portion, the electrode plate start end and electrode plate end end are arranged in a curved portion.

[0094] In the above embodiment, the first electrode body 600 and the second electrode body 700 are so-called horizontally wound electrode bodies in which the winding axis is perpendicular to the cover body 120. However, they may also be so-called vertically wound electrode bodies in which the winding axis is parallel to the cover body 120. In this case as well, the same configuration as in the above embodiment can be achieved by forming tabs on the vertically wound electrode body.

[0095] Embodiments constructed by arbitrarily combining the above embodiments and modifications are also included within the scope of the present invention.

[0096] This invention can be realized not only as such an energy storage element, but also as a combination of a first electrode body and a second electrode body. [Industrial applicability]

[0097] This invention can be applied to energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0098] 10 Energy storage elements 100 containers 110 Container body 120 Lid 200 electrode terminal 300 Upper gasket 400 Lower gasket 500 Current collector 600, 600a, 600b First electrode body 610 First electrode main body part 611, 612 First electrode body flat part 611a, 612a First electrode plate starting end 612b First plate end 613, 614 First electrode body curved section 620 First positive electrode tab 630 First negative electrode tab 640, 650 First plate 641, 651, 741, 751 tabs 661, 662 First Separator 700, 700a, 700b, 700c Second electrode body 710 Second electrode main body part 711, 712 Second electrode body flat part 711a, 712a Starting end of second electrode plate 711b Second plate end 713, 714 Second electrode body curved section 720 Second positive electrode tab 730 Second negative electrode tab 740, 750 Second plate 761, 762 Second Separator

Claims

1. A power storage element comprising a first electrode body formed by winding a first electrode plate and a second electrode body formed by winding a second electrode plate, The first electrode body comprises a first electrode body main body portion and tabs protruding from a part of the first electrode body main body portion, which are the positive electrode side tab and the negative electrode side tab, a first positive electrode tab and a first negative electrode tab. The second electrode body comprises a second electrode body main body portion and tabs protruding from a part of the second electrode body main body portion, which are the positive electrode side tab and the negative electrode side tab, respectively. The first electrode body portion has a first electrode plate end portion, which is the winding end portion of the first electrode plate, at a position opposite to the second electrode body portion. The second electrode body portion has a second electrode plate end portion, which is the winding end portion of the second electrode plate, at a position opposite to the first electrode body portion. The first electrode plate end portion and the second electrode plate end portion are positioned so as not to overlap when viewed from the direction in which the first electrode body and the second electrode body are aligned. Energy storage element.

2. The direction from the first positive electrode tab towards the first negative electrode tab and the direction from the second positive electrode tab towards the second negative electrode tab are the same. The energy storage element according to claim 1.

3. At least one of the first positive electrode tab and the first negative electrode tab is positioned to protrude from a portion of the first electrode body that is opposite to the second electrode body, rather than from a portion of the first electrode body that is facing the second electrode body. The tab of the second positive electrode tab and the tab of the second negative electrode tab having the same polarity as at least one of the tabs is positioned to protrude from a portion of the second electrode body body that is opposite to the first electrode body body, rather than from a portion of the second electrode body body body that is facing the first electrode body body body. The energy storage element according to claim 2.

4. At least one of the first electrode body and the second electrode body has a pair of curved portions formed by winding at least one of the first electrode plate and the second electrode plate, and a flat portion connecting the pair of curved portions, At least one of the first electrode plate end portion and the second electrode plate end portion is arranged in the flat portion. The energy storage element according to any one of claims 1 to 3.

5. The first electrode plate end portion extends toward the second electrode plate end portion at the portion of the first electrode body body facing the second electrode body body, The second electrode plate end portion extends toward the first electrode plate end portion at the portion of the second electrode body body facing the first electrode body body. The energy storage element according to any one of claims 1 to 4.

Images